当θ很小时,θ≈sinθ≈tanθ.这个近似式在物理中有很多用途.1.推导公式(1)单摆周期单摆是用一根不计质量,不计伸缩的细线系一个可视为质点的小球.如图1所示,设摆球的质量为m,摆长为l,最大摆角α≤5°.摆球所受的回复力是重力的切向分力,即 When θ is small, θ ≈ sin θ ≈ tan θ. This approximation has many uses in physics. 1. Derivation of equations (1) Single pendulum cycle Single pendulum is a thin wire that does not count mass, not counting telescopic The pellet of the particle, as shown in Fig. 1, has a pendulum mass of m, a pendulum length of l, and a maximum swing angle of α≤5°. The restoring force of the pendulum ball is the tangential force of gravity, that is,